1. Field of the Invention
The present invention relates generally to a voice warning system for an automotive vehicle, and more particularly to a voice volume controller provided for the voice warning system whereby the voice volume is automatically adjusted to an appropriate sound level according to changes in the noise level within the passenger compartment. In this case, noise includes all the sound within the passenger compartment other than the warning voice produced from the voice warning system of the present invention.
2. Description of the Prior Art
Heretofore, as means for informing the driver of various vehicle operating conditions, there have been used various meters with pointers and various warning indication lamps. In addition, recently, there have appeared vehicles in which a computer is mounted so as to display digitally various vehicle operating conditions whenever the driver depresses pushbuttons to obtain the vehicle conditions. That is to say, in these devices, the driver is informed of the vehicle conditions through the sense of sight. On the other hand, as devices by which the driver is informed through the sense of hearing, there have been used various devices which produce a simple warning sound such as buzzer or chime.
Although these conventional warning devices which depend upon the sense of sight have the advantage that a number of vehicle conditions can be displayed at the same time, it is comparatively difficult to attract the driver's attention and to give the driver complicated information. Also, in the case of the conventional devices which depend upon the sense of hearing, it is difficult to inform the driver of different items of information, even if the device can attract the driver's attention.
Therefore, recently, various voice warning systems have come to be used for vehicles by which the driver can hear various vehicle operating conditions such as the distance traveled detected by a trip meter, the amount of fuel consumed and so on, in voice form.
When such a device as described above is used for an automotive vehicle, it is possible to attract the driver's attention well and also to inform the driver of relatively complicated vehicle operating conditions without any difficulties. In this case, however, when the passenger compartment is noisy because the car radio or other equipment is turned on, because the passengers are talking to each other, or because the car is traveling along a noisy street, it is impossible to hear the voice warning information clearly unless the volume is adjusted to a higher level.
However, if the voice volume is permanently adjusted to a high level, the problem arises that the voice is too loud, especially when the passenger compartment is quiet or when the vehicle is traveling along a quiet street at night.
Therefore, there is a need for a voice warning system for an automotive vehicle by which the driver can always hear the warning voice at an appropriate sound level.